1. Field of the Invention
This invention relates to the field of integrated circuit packaging, and in particular to a substrate that provides efficient thermal conductivity.
2. Description of Related Art
High-current-drawing circuits produce heat that must be dissipated. U.S. Pat. No. 6,121,680 discloses the use of a heat-fin structure that is affixed to the top of an integrated circuit to dissipate heat from the integrated circuit to the air around the fins of the heat-fin structure. U.S. Pat. No. 5,960,863 teaches the use of a dissipating block consisting of several overlapping screen plates that is bolted to a thermally conductive base plate that is fastened to the integrated circuit from which the heat is dissipated.
U.S. Pat. No. 5,309,321 teaches a wire mesh that is encapsulated into a non-electrically conductive thermosetting or thermoplastic material that forms a housing that encloses an integrated circuit chip. U.S. Pat. No. 5,500,555 teaches a substrate for mounting an integrated circuit chip that comprises a sandwich of insulating prepeg material and a thermally conductive mesh or screen.
Each of the prior art embodiments rely upon a layer of insulating material that separates the thermally-conductive material from conductors of the integrated circuit, or from conductors of the printed circuit board upon which the integrated circuit device is mounted. Each of these prior art embodiments requires one or more processing steps to create the multilayer (conductor, non-conductor) structure that dissipates heat from the integrated circuit. Additionally, in each of the prior art embodiments, a separate heat-dissipation structure is used to dissipate the heat produced by the integrated circuit.
It is an object of this invention to provide a cost-effective means to dissipate heat from a circuit, such as an integrated circuit chip. It is a further object of this invention to provide a heat dissipation device that allows the dissipation of heat from a circuit to multiple traces on a printed-circuit board. It is a further object of this invention to provide a heat dissipation device that minimizes the risk of short circuits caused by the thermally conductive material in the heat dissipation device.
These objects, and others, are achieved by providing a substrate material that contains a non-electrically-conductive mesh of thermally-conductive material. Because the mesh is electrically-non-conductive, it can purposely be configured to contact any and all of the circuit traces that are proximate to the substrate, thereby using the circuit traces as thermally-coupled heat sinks. In a preferred embodiment, the thermally-conductive mesh replaces the structural fiberglass mesh that is conventionally used in substrates, thereby allowing the mesh to serve a dual structural and thermal function.